diff --git a/src/Record/MP4Muxer.cpp b/src/Record/MP4Muxer.cpp
index 0b4357a6..11747126 100644
--- a/src/Record/MP4Muxer.cpp
+++ b/src/Record/MP4Muxer.cpp
@@ -61,6 +61,16 @@ bool MP4MuxerInterface::haveVideo() const {
     return _have_video;
 }
 
+uint64_t MP4MuxerInterface::getDuration() const {
+    uint64_t ret = 0;
+    for (auto &pr : _codec_to_trackid) {
+        if (pr.second.stamp.getRelativeStamp() > ret) {
+            ret = pr.second.stamp.getRelativeStamp();
+        }
+    }
+    return ret;
+}
+
 void MP4MuxerInterface::resetTracks() {
     _started = false;
     _have_video = false;
diff --git a/src/Record/MP4Muxer.h b/src/Record/MP4Muxer.h
index 25fd0447..877b05ff 100644
--- a/src/Record/MP4Muxer.h
+++ b/src/Record/MP4Muxer.h
@@ -58,6 +58,11 @@ public:
      */
     void initSegment();
 
+    /**
+     * 获取mp4时长,单位毫秒
+     */
+    uint64_t getDuration() const;
+
 protected:
     virtual MP4FileIO::Writer createWriter() = 0;
 
@@ -73,7 +78,7 @@ private:
         Stamp stamp;
     };
     std::unordered_map<int, track_info> _codec_to_trackid;
-    FrameMerger _frame_merger{FrameMerger::mp4_nal_size};
+    FrameMerger _frame_merger { FrameMerger::mp4_nal_size };
 };
 
 class MP4Muxer : public MP4MuxerInterface{
diff --git a/src/Record/MP4Recorder.cpp b/src/Record/MP4Recorder.cpp
index d527bb27..efb011fc 100644
--- a/src/Record/MP4Recorder.cpp
+++ b/src/Record/MP4Recorder.cpp
@@ -70,24 +70,21 @@ void MP4Recorder::asyncClose() {
     auto full_path = _full_path;
     auto info = _info;
     WorkThreadPool::Instance().getExecutor()->async([muxer, full_path_tmp, full_path, info]() mutable {
-        //获取文件录制时间，放在关闭mp4之前是为了忽略关闭mp4执行时间
-        info.time_len = (float) (::time(NULL) - info.start_time);
-        //关闭mp4非常耗时，所以要放在后台线程执行
+        info.time_len = muxer->getDuration() / 1000.0f;
+        // 关闭mp4可能非常耗时，所以要放在后台线程执行
         muxer->closeMP4();
-        
-        if(!full_path_tmp.empty()) {
-            //获取文件大小
+        if (!full_path_tmp.empty()) {
+            // 获取文件大小
             info.file_size = File::fileSize(full_path_tmp.data());
             if (info.file_size < 1024) {
-                //录像文件太小，删除之
+                // 录像文件太小，删除之
                 File::delete_file(full_path_tmp.data());
                 return;
             }
-            //临时文件名改成正式文件名，防止mp4未完成时被访问
+            // 临时文件名改成正式文件名，防止mp4未完成时被访问
             rename(full_path_tmp.data(), full_path.data());
         }
-
-        /////record 业务逻辑//////
+        //触发mp4录制切片生成事件
         NoticeCenter::Instance().emitEvent(Broadcast::kBroadcastRecordMP4, info);
     });
 }